Answer:
The planetary system is 9 billion years old
Explanation:
In 4.5 billion years, the meteorite was half uranium and half lead. For this amount of uranium to be reduced by half again (reaching 1/4 uranium and 3/4 lead), another 4.5 billion years must have passed. Then, the planetary system should be 9 (2 x 4.5) billion years old.